This invention generally pertains to a high temperature capable flange. In particular, various embodiments of the present invention relate to a boltless flange for use in turbo-machinery at the compressor discharge.
A gas turbine engine is typical of turbo-machinery in which the concept described herein may be advantageously employed. It is well known that a gas turbine engine conventionally comprises a compressor for compressing inlet air to an increased pressure for combustion in a combustion chamber. A mixture of fuel and the increased pressure air is burned in the combustion chamber to generate a high temperature gaseous flow stream for causing rotation of turbine blades within the turbine. The turbine blades convert the energy from the high temperature gaseous flow stream into kinetic energy, which is utilized to turn a propeller, fan, or other device. Further, the high temperature gaseous flow stream may be used directly as thrust for providing motive power, such as in a turbine jet engine.
A long recognized need by many gas turbine engine designers is to attain higher operating temperatures in order to achieve both a greater thermodynamic efficiency and an increase in power output per unit of engine weight. Theoretically, a gas turbine engine would operate at stoichiometric combustion in order to extract the greatest possible energy value from the fuel consumed. However, temperatures at stoichiometric and even near stoichiometric combustion are generally beyond the endurance capabilities of traditional metallic gas turbine engine components. Similarly, improvements to efficiency may result from increased pressure ratios in the compressor of the gas turbine engine. These increased pressure ratios result in higher compressor discharge temperatures which can be beyond the endurance capabilities of traditional metallic gas turbine engine components, such as bolts, found at the compressor discharge.
Many of the traditional flange designs for use in gas turbine engines make use of threaded fasteners such as screws and bolts. Such designs present difficulties in the high temperature environment encountered in gas turbine engines. As temperatures grow higher because of the desire for increased efficiency or because of increasing inlet temperatures associated with higher speed aircraft, existing bolt materials are found to be unsuitable. In particular, the compressor discharge temperatures are becoming greater than that allowed by traditional bolt materials. In the hostile environment of the gas turbine engine the bolt threading can seize up making disassembly, as may be necessary for repair, difficult if not impossible. Even more importantly, each thread of a bolt may act as a stress riser where fatigue and consequent fracture is more likely to occur.
Referring to FIG. 1 there is illustrated a configuration of an inner combustor case flange design. The illustrated inner combustor case flange design configuration comprises an inner case 110, hanger 120, outlet guide vane (xe2x80x9cOGVxe2x80x9d) hanger 104, and OGV assembly 100 held together by a first series of bolts 170 spaced around the circumference of a first bolt circle. It should be understood that bolt 170 is actually one bolt in a larger bolt circle that is centered around a central axis. When the flange illustrated in FIG. 1 is used at the compressor discharge location, there will often be a compressor discharge pressure (xe2x80x9cCDPxe2x80x9d) seal 140 that is attached to the OGV hanger 104 by a second series of bolts, such as bolts 180, spaced around the circumference of a second bolt circle.
Each of the bolts 170 in the first bolt circle has a shank 173 extending between a threaded end 171 and a head end 172 having head 172a. The shank 173 has a threaded portion 174 extending to the right of inner case 110 and is held in place by a locking nut 175 that has internal threading matching the external threading 174 on bolt 170. Similarly, each bolt 180 that is part of the second bolt circle has a shank 183 extending between a threaded end 181 and a head end 182 with a head 182a. The shank 183 has a threaded portion 184 that extends through the compressor discharge pressure seal 140 and the OGV hanger 104. Each bolt 180 is held in place by a locking nut 185 having an internal threading that matches the external threading of threaded portion 184 of bolt 180.
As illustrated in FIG. 1 the bolts 170, 180 engage locking nuts 175, 185 respectively which are attached to the right most flange of the assembly. Diametral locations of the five pieces (flanges) are controlled through a total of eight close tolerance pilot diameters and ten flange faces. Tangential orientation of the OGV assembly 100 is provided by a locating pin or a non-uniform bolt pattern in the flange.
There remains a need for flange designs capable of operating in high temperature environments. The present invention satisfies this need in a novel and nonobvious way.
The invention is a high temperature capable boltless flange for use in turbo-machinery. Instead of bolts, a plurality of substantially radially extending pins are used in the high temperature capable flange.
One embodiment of the invention is an apparatus for use in a gas turbine engine. The apparatus comprises a hanger, an inner case and a first pin. The hanger has a ring shaped portion substantially centered around an axis. The ring shaped portion of the hanger includes a first plurality of passages. Each of the first plurality of passages extends substantially radially with respect to the axis. The inner case has a ring shaped portion substantially centered around the axis. The ring shaped portion of the inner case is positioned radially outward from the ring shaped portion of the hanger. The ring shaped portion of the inner case includes a plurality of openings, each of the plurality of openings extending substantially radially with respect to the axis. At least one of the plurality of openings is substantially aligned with at least one of the first plurality of passages. A first pin extends between a first end and a second end. A first portion of the first pin and the first end are both positioned within said at least one of the plurality of openings. A second portion of the first pin is positioned within said at least one of the first plurality of passages to couple the hanger to the inner case.
Another embodiment of the apparatus of the present invention is an apparatus for use in a gas turbine engine comprising a hanger, a seal and a first pin. The hanger has a ring shaped portion substantially centered around an axis. The ring shaped portion of the hanger includes a first plurality of passages, each of the first plurality of passages extending substantially radially with respect to the axis. The seal has a ring shaped portion substantially centered around the axis, the ring shaped portion of the seal being positioned radially inward of the ring shaped portion of the hanger. The ring shaped portion of the seal includes a first plurality of orifices extending substantially radially with respect to the axis. At least one of the first plurality of orifices is substantially aligned with at least one of the first plurality of passages. A first pin extends between a first end and a second end. The first end and a first portion of the first pin are positioned within said at least one of the first plurality of passages. Also, a second portion of the first pin is positioned within said at least one of the first plurality of orifices to couple the hanger to the seal.
A third embodiment of the present invention is an apparatus for use in a gas turbine engine comprising a hanger, an inner case, a seal, means for coupling the hanger to the inner case and means for coupling the hanger to the seal. The hanger has a ring shaped portion substantially centered around an axis. The inner case has a ring shaped portion substantially centered around the axis. The ring shaped portion of the inner case is positioned radially outward of the ring shaped portion of the hanger. The seal has a ring shaped portion substantially centered around the axis. The ring shaped portion of the seal is positioned radially inward of the ring shaped portion of the hanger.
One object of the present invention is to provide a unique high temperature capable flange where the use of bolts is minimized or eliminated.
Related objects and advantages of the present invention will be apparent from the following description.